Web service mutual authentication

Hi, i need to send a XML/SOAP message to a web service via SSL with
mutual athentication. The XML file needs to be signed with a
certificate. I have the certificate and i almost solved this part of the
problem, i used the gem signer to sign the XML file. Now i trying to
send this signed XML to the web service via SSL with mutual

I tried use the savon gem and i did this:

client = Savon.client(
:wsdl => WSDL_URL,
:log_level => :debug,
:log => true,
:ssl_verify_mode => :none,
:ssl_cert_file => ‘cert.pem’,
:ssl_cert_key_file => ‘privateKey.key’,
:ssl_cert_key_password => ‘’

And when i called any savon method, like ‘client.operations’, return
this error: SSL_CTX_use_PrivateKey: key values mismatch

What is the best way to solve it?
Where can i find some code examples?